The present invention relates generally to hydraulic pressure control, more particularly to a hydraulic braking pressure control system for motor vehicles. The present invention may be embodied, for example, in an anti-skid control system, but it will be appreciated that it is also useful in other applications such as a vehicle height control system.
Various types of anti-skid control systems for motor vehicles have been developed to control the speed of each of the wheels of a motor vehicle. The purpose is to prevent a decrease in vehicle safety due to locking of the wheels on vehicle braking operation. One known arrangement is disclosed in Japanese Patent Publication No. 51-6308, in which the control of hydraulic braking pressure is performed by changing the pressure-increasing and pressure-decreasing proportions in accordance with a control of the duty ratio of an output signal to a hydraulic pressure adjusting device.
Although such a prior art technique provides satisfactory results for meeting the requirements imposed in anti-skid control, it would be advantageous from the viewpoint of more effectively performing the hydraulic pressure control to provide a new hydraulic pressure control system for a motor vehicle.